CN100372917C - Cooling fluid in use for super fine milling functional crystal of potassium dihydrogen phosphate - Google Patents

Abstract

This invention discloses a cooling liquid for ultraprecision milling of functional potassium dihydrogen phosphate crystals. Since potassium dihydrogen phosphate crystals have such characeristics as easy deliquescence, high softness, high brittleness, high temperature-change sensitivity and easy cracking, traditional cooling liquids may cause surface fogging phenomenon or even surface cracking. The cooling liquid in this invention is composed of: aviation kerosene as the matrix, EDTA 1.598-3.2 mg/L and sulfosalicylic acid 0.031-0.1 mg/L. The cooling liquid can largely reduce surface roughness of processed crystals, lower surface residual stress, inhibit surface fragile damage and avoid surface fogging phenomenon.

Description

A kind of cooling fluid when being used for the milling of functional crystal potassium primary phosphate ultraprecise

Technical field

The present invention relates to a kind of cooling fluid, be specifically related to a kind of cooling fluid when being used for the milling of functional crystal potassium primary phosphate (KDP) ultraprecise.

Background technology

Potassium primary phosphate (KDP) crystal is a kind of inorganic nonlinear optical material of excellent property, it has a wide range of applications in technical fields such as laser inertial confinement nucleosynthesis, laser communication, for the working accuracy and the surface quality that improve the KDP crystal photoelement, various countries drop into a large amount of human and material resources one after another its processing technology are studied.At present, adopt the method for single-point diamond turning (SPDT) that the KDP crystal is processed in the plasticity pattern both at home and abroad usually.Abroad the behaviour in service to cooling fluid has reflected that cooling fluid can effectively improve KDP crystalline processing quality, but because the KDP crystal has important role at aspects such as Aeronautics and Astronautics and national defence, its correlation technique is maintained secrecy to China's emphasis.And domestic chemical ingredients and problem such as the optimum proportion of the mechanism of action of KDP crystal finished surface, cooling fluid composition and machining dosage for cooling fluid also further investigate, so China does not use cooling fluid yet in the KDP crystalline course of processing.This shows that the research cooling fluid is promoted the application of cooling fluid in China KDP crystal course of processing and had important theory and realistic meaning the influence of KDP plane of crystal quality.

The KDP crystal at room temperature belongs to tetragonal system, has the intensive anisotropy.In the KDP crystalline SPDT course of processing, use cooling fluid can reduce the frictional coefficient of cutter and workpiece, can reduce cutting force significantly like this, reduce its fluctuating range, thereby can stablize plastic processing, obtain surface quality comparatively uniformly.In addition, cooling fluid can also be by scrap fallaway, reduce the finished surface temperature fluctuation, reduce effects such as sub-surface damage, thereby further improves KDP crystalline machined surface quality.But because the KDP crystal has easy deliquescence, matter is soft, fragility is high, to characteristics such as temperature variation are responsive and easy to crack, easily at its finished surface " atomizing " phenomenon appears when using cooling fluid, the crystalline situation that ftractures can appear when serious.Therefore, must develop a kind of special cooling fluid when being applicable to the milling of KDP crystal ultraprecise, thereby further improve the machined surface quality of crystal part.

Summary of the invention

Because the KDP crystal has easy deliquescence, matter is soft, fragility is high, to characteristics such as temperature variation are responsive and easy to crack, when using cooling easily at its finished surface " atomizing " phenomenon appears, crystalline cracking situation can appear when serious, the present invention has developed a kind of special cooling fluid when being applicable to the milling of potassium dihydrogen phosphate crystal ultraprecise for this reason, thereby further improves the machined surface quality of crystal part.

Cooling fluid when being used for the milling of functional crystal KDP ultraprecise of the present invention is made up of aviation kerosene, EDTA and SSal, wherein adopt aviation kerosene as matrix, the addition of EDTA is 1.598mg/L～3.2mg/L, and the addition of sulphosalicylic acid (SSal) is 0.031mg/L～0.1mg/L.

Because the easy deliquescence of KDP crystal, thereby can not be moisture in the cooling fluid.Moreover, impurity existence such as each metal ion species can not be arranged in the cooling fluid, otherwise, very easily the KDP plane of crystal is produced absorption, and can quicken plane of crystal atomizing, increase the weight of the crystal scattering, bring out its two-photon absorption etc., thereby can further reduce KDP crystalline mechanical property and use properties.

About the impurity metal ion in the cooling fluid crystal is added the mechanism that influences in man-hour, specifically comprises following several aspect:

The laser wavelength juxtaposition that inputs or outputs when using (1) because the intrinsic absorption band of metal ion is different from the KDP crystal, and their absorption can cause new UV absorption band, and with the KDP crystal has seriously reduced the efficient of frequency inverted device.And the impurity defect zone is big more a lot of than the intrinsic absorption to the absorption of laser.After the impurity defect zone absorbs laser energy consumingly, temperatures at localized regions raises, when temperature reaches a certain threshold value, during as the fusing point of material, transformation temperature, matrix fusing around the impurity, gas produce thermal stresses, thermal shock wave, so that the damage of crystal generation induced with laser.

(2) impurity metal ion has the quantity of electric charge higher than potassium ion, after they are adsorbed on the KDP plane of crystal, can cause serious lattice deformability on the one hand, causes partial surface stress inequality, even the physicalies such as fracture toughness property on influence surface; Can bring out the H of near zone on the other hand ⁺The room, this proton room and PO ₄ ^-Hole of O ion trap can form (HPO ₄)-activation center, it is a defective that can produce two-photon absorption.When projectile energy was lower, the absorption in the KDP crystal was linear.Along with the increase of projectile energy, crystal generation two-photon absorption.After crystal absorbs high-octane laser, cause local photo-thermal to strengthen, the lattice localized vibration is strengthened, form high stress areas in the KDP crystal, destroyed the stability of lattice, cause chemical bond rupture, perhaps the part undergoes phase transition, perhaps local melting.

(3) impurity metal ion absorption KDP plane of crystal can produce the very strong phosphoric acid salt of water absorbability.According to the chemical reaction equilibrium theory, divalence and tervalent metal ion and KH ₂PO ₄Reaction below general the existence.M representation metal ion wherein, the value of a is 2 or 3.Its reaction formula is as follows:

M ^a++aH ₂PO ₄ ^-□M(H ₂PO ₄ ^-) ^a (1)

$M^{a+}+\frac{a}{2}\mathrm{HP}{O}_4^{2-}\→M{\left(\mathrm{HP}{O}_4^{2-}\right)}^{\frac{a}{2}}\↓$

$M^{a+}+\frac{a}{3}P{O}_4^{3-}\→M{\left(P{O}_4^{3-}\right)}^{\frac{a}{3}}\↓$

In addition, it is strong that the phosphorus oxygen tetrahedron in the KDP crystal contains π, thereby have very strong coordination ability, can form title complex with many metal ions.As Fe ³⁺And PO ₄ ^3-Can generate the title complex [Fe (HPO of colourless solubility ₄) ₂] ^-[Fe (PO ₄) ₂] ^3-, utilize this character, PO commonly used on the analytical chemistry ₄ ^3-Shelter Fe ³⁺Ion.

According to top analysis as can be seen, as containing Ca, Zn plasma in the impurity, the phosphoric acid salt of generation just has extremely strong water absorbability.This class phosphoric acid salt even can be in the environment of high-cleanness, high sees through the anti-reflection film of plane of crystal and absorb moisture, thereby the zone below anti-reflection film produces atomizing, also can cause the etching of plane of crystal when serious.Its result can increase the weight of the crystalline scattering, causes the damage of other element in KDP optical element and the light path, and this is extremely harmful for high power laser system.

Based on above-mentioned analysis, in the process for preparation of cooling fluid, the present invention has determined the 16 kind principal elements stronger to KDP plane of crystal adsorptive power, is divided into M by its valency ²⁺: Fe ²⁺, Co ²⁺, Mn ²⁺, Ni ²⁺, Mg ²⁺, Cu ²⁺, Cd ²⁺, Zn ²⁺, Ca ²⁺, Sr ²⁺, Ba ²⁺M ³⁺: Al ³⁺, Fe ³⁺, Mn ³⁺, Cr ³⁺, Ce ³⁺, Y ³⁺, La ³⁺

The present invention adopts the matrix of water-free aviation kerosene as its cooling fluid, traces it to its cause, and mainly is that matrix is not moisture because aviation kerosene is to be made through steps such as distillations, hydrocracking by natural oil, and impurity composition and content thereof are less.In order to survey its impurity composition, adopt the metal ion content in the aes determination aviation kerosene.Concrete content sees Table 1.

The content of actual harm metallic element in table 1 aviation kerosene

Element	Content (mg/L)	Element	Content (mg/L)	Element	Content (mg/L)
						Sr Al Fe Zn	0.00029 0.05180 0.08575 0.02208	Ba Mg Ca La	0.00925 0.00825 0.04805 0.00000	Cd Ni Ce Y	0.00082 0.00070 0.00052 0.00006

Cu Mn

0.00698 0.00266

Cr

0.00031

Co

0.00000

After the foreign matter content in knowing cooling fluid, the present invention adopts the method for adding complexing agent can remove these impurity compositions.This is because complexing agent can effectively be eliminated the adsorption activity of metal ion, the complexing product that forms with metal ion has very high stability, and complexing agent commonly used greatly can be simultaneously and the plurality of impurities complexing, thereby can reach the removal purpose with less complexing agent kind.

By a large amount of experimental studies have found that, ethylenediamine tetraacetic acid (EDTA) (EDTA, H commonly used ₄Y represents) to Fe ²⁺, Co ²⁺, Mn ²⁺, Ni ²⁺, Mg ²⁺, Cd ²⁺, Zn ²⁺, Ca ²⁺, Sr ²⁺, Ba ²⁺, Al ³⁺, Fe ³⁺, Mn ³⁺, La ³⁺The complexing effect better, and SSal is to Y ³⁺, Cu ²⁺, Cr ³⁺And Ce ³⁺Has bigger Complex effect coefficient.

According to the molecular weight of EDTA and SSal, and they and the complexing ratio of metal ion, the mass concentration of metal ion is scaled volumetric molar concentration after, can obtain the additive amount that needs.Table 2 is the metal ion volumetric molar concentrations after converting.Thus, the EDTA and the SSal consumption that calculate of the present invention is respectively 1.598mg/L and 0.031mg/L.Consider the pollution that may exist in the course of processing and the weighing precision of electronic scales, the addition of additive has been made suitable adjustment: EDTA addition 3.2mg/L, SSal addition 0.1mg/L.

The volumetric molar concentration of metal ion in table 2 aviation kerosene

Element	Content (mol/L)	Element	Content (mol/L)	Element	Content (mol/L)
						Sr Al Fe Zn Cu Mn	0.00000000331 0.00000192000 0.00000153540 0.00000033767 0.00000010984 0.00000004842	Ba Mg Ca La Cr	0.00000006736 0.00000033944 0.00000119900 0.00000000000 0.00000000597	Cd Ni Ce Y Co	0.00000000730 0.00000001193 0.00000000380 0.00000000068 0.00000000000

By a large amount of experimental analyses, the cooling fluid when the present invention has finally obtained to be used for the milling of KDP crystal ultraprecise utilizes this cooling fluid can greatly improve the machined surface quality of part.The present invention has following advantage:

(1) adopt this cooling fluid can significantly reduce the machined surface roughness of part;

(2) this cooling fluid helps reducing the unrelieved stress of finished surface;

(3) cooling fluid can obviously reduce the brittle damage of piece surface;

(4) use this cooling fluid can't produce " atomizing " phenomenon at finished surface.

Embodiment

Embodiment one: the cooling fluid of present embodiment is made up of aviation kerosene, EDTA and SSal, wherein adopts aviation kerosene as matrix, and the addition of EDTA is 1.598mg/L～3.2mg/L, and the addition of SSal is 0.031mg/L～0.1mg/L.

Embodiment two: what present embodiment and embodiment one were different is, the addition of EDTA is 1.6mg/L, and the addition of SSal is 0.04mg/L.

Embodiment three: what present embodiment and embodiment one were different is, the addition of EDTA is 2.4mg/L, and the addition of SSal is 0.062mg/L.

Embodiment four: what present embodiment and embodiment one were different is, the addition of EDTA is 3.2mg/L, and the addition of SSal is 0.1mg/L.

Experiment condition: smooth turning lathe maximum speed of spindle 1600r/min, adopt the grating chi to realize that the numeral of feeding device shows full accuracy 0.001mm.Diamond cutter is the circular arc sword, anterior angle-10 °, arc radius 8mm.Selected cutting parameter is: speed of mainshaft 800rpm, speed of feed 10 μ m/r, back engagement of the cutting edge 20 μ m.

(1) cooling fluid his-and-hers watches The surface roughness affected

The roughness concentration instrument is the NanoscopeIII type AFM that U.S. DI company produces, and the roughness of 7 positions of plane of crystal is measured the gained data be shown in table 3.

The surfaceness (nm) of table 3 KDP crystal SPDT cutting

Cutting side	Measure ginseng	A	B	C	D	E	F	G
									The dry type wet type	Rmax Ra Rmax Ra	193.63 9.367 134.93 16.045	203.03 16.657 155.50 23.311	153.51 12.242 152.55 22.989	424.71 15.919 147.78 20.786	227.97 10.287 167.98 19.423	303.66 4.750 156.17 19.286	271.72 11.733 145.48 17.496

Be not difficult to find out by table 3 analysis, in the KDP crystalline SPDT course of processing, use cooling fluid, can effectively improve the stability of plastic processing, reduce surface average roughness and surperficial maximal roughness, reduce the fluctuating of surface topography, thereby obtain surface quality comparatively uniformly.

(2) cooling fluid is to the influence of surface residual stress

Surface residual stress detects the XSTRESS3000 type residual stress measurement instrument that used instrument is an AST-STRESSTECH company.The gained data are as shown in table 4.

The unrelieved stress of table 4 KDP crystal SPDT dry type and wet type cutting

Cutting way	A	B	C	D	E	F	G
								The dry type wet type	-11.164 -1.085	349.526 8.650	160.886 73.866	-59.146 124.195	43.728 81.744	31.574 5.301	160.760 31.574

Data analysis by table 4 as can be seen, the unrelieved stress and the fluctuating range thereof of wet type cutting all are better than DRY CUTTING, thereby the wet type cutting has better surface quality, this is consistent with the situation of surperficial maximal roughness.They reflect uses cooling fluid can effectively stablize the SPDT course of processing, reduces KDP crystalline surface damage, promotes the homogenization of surface quality, finally improves the crystalline machined surface quality.

(3) cooling fluid is to the influence of brittle damage

The NanoscopeIII type AFM that adopts U.S. DI company to produce carries out the analysis of brittle damage to its finished surface, is shown in Table 5.

Table 5 KDP crystalline surface brittleness fracture pit and surface crack

Cutting way	The brittle rupture of I class	The brittle rupture of II class	The top layer crackle
				The dry type wet type	7 1	16 20	23 8

Can find by contrast KDP crystalline dry type and wet type cutting, though bigger speed of feed has been adopted in the wet type cutting, but still shown greater advantage in surfaceness, surface residual stress, local brittle damage several respects, this has proved absolutely that cooling fluid has good improvement effect to the KDP crystalline SPDT course of processing, can effectively improve KDP crystalline suface processing quality, obtain the KDP crystal photoelement of better quality.

(4) cooling fluid is to the influence of KDP plane of crystal atomizing

Do not find any atomizing point with the plane of crystal after the microscopic examination processing, this conforms to the fact that aviation kerosene has high-cleanness, high, and basic moisture-free in the cooling fluid has been described.

Claims (4)

1. cooling fluid when being used for the milling of functional crystal potassium primary phosphate ultraprecise, it is characterized in that described cooling fluid is made up of aviation kerosene, ethylenediamine tetraacetic acid (EDTA) and sulphosalicylic acid, wherein adopt aviation kerosene as matrix, the addition of ethylenediamine tetraacetic acid (EDTA) is 1.598mg/L～3.2mg/L, and the addition of sulphosalicylic acid is 0.031mg/L～0.1mg/L.

2. a kind of cooling fluid when being used for the milling of functional crystal potassium primary phosphate ultraprecise according to claim 1, the addition that it is characterized in that described ethylenediamine tetraacetic acid (EDTA) is 1.6mg/L, the addition of sulphosalicylic acid is 0.04mg/L.

3. a kind of cooling fluid when being used for the milling of functional crystal potassium primary phosphate ultraprecise according to claim 1, the addition that it is characterized in that described ethylenediamine tetraacetic acid (EDTA) is 3.2mg/L, the addition of sulphosalicylic acid is 0.1mg/L.

4. a kind of cooling fluid when being used for the milling of functional crystal potassium primary phosphate ultraprecise according to claim 1, the addition that it is characterized in that described ethylenediamine tetraacetic acid (EDTA) is 2.4mg/L, the addition of sulphosalicylic acid is 0.062mg/L.